Variable camber rolling mill rolls have therefore been proposed, which permit adaptation of the camber to the thickness fault measured in the transverse direction of the strip. Rolls of this kind comprise a fixed support bearing on the frame of the roll stand and a tubular casing mounted for rotation about the fixed support, in such a manner that a space is formed between the fixed support and the inner surface of the tubular casing. The forces applied to the roll during rolling are taken up by means of jacks, whose chambers are fastened to the fixed support and whose pistons, directed radially relative to the rolls, have, at their ends directed towards the inner surface of the casing, a chamber receiving the pressurized fluid feeding the jack. Between the piston of each jack and the inner surface of the casing a film of fluid under pressure is thus formed, constituting a bearing on which the tubular casing rests.
The jacks are aligned in the axial direction of the roll, corresponding to the transverse direction of the sheet, and are regularly spaced in that direction. These jacks can be independently fed with pressurized fluid, thus making it possible to control the camber of the roll, along the length of the roll, extremely accurately.
This control of the camber is achieved by adjusting the pressure of the fluid in the different jacks in accordance with the readings of thickness gauges distributed in the transverse direction of the sheet at the outlet of the roll stand.
A process of this kind, which is described, for example, in French Pat. No. 2,360,713, nevertheless does not achieve great accuracy with regard to the adjustment of thickness, or sufficient stability in the course of the adjustment, because the deformations of the casing by the different jacks interfere with one another. Full use is therefore not made of the advantages which should be provided by an accurate camber adjusting device.